I think the main reason the 'heretical' Albigensians, Gnostics, Illuminati, Cathars and etc. are so vilified today is that they saw the danger of the Church 300 years ago and fought in secret against the ever more powerful and sinister Vatican. In a way one could say the same about Jews, who 1600 years earlier had dared to drive the Romans out of Jerusalem for a time, inspiring countless other inconvenient rebellions against Roman rule. 200 years later Emperor Constantine convened the Nicene Council, had the Bible rewritten to be more male-dominated and empire-friendly. As the saying goes, never pick a fight with a guy who buys ink by the metric tonne, and the Roman Church certainly qualified in that regard, and  backed that ink up with sword, sandal, and sail for the next 1700 years.